How small can a folding bike become without sacrificing the ability to ride comfortably?

The Sada Bike is one experiment: The full-sized frame folds down to the size of an umbrella, and full-sized wheels pop off so everything can fit into a backpack.

“It started as a joke,” says Gianluca Sada, who created the bike as a design student. “But then I decided to devote my engineering study to developing it. Folding bikes are usually too small, with a frame and wheels that are portable but unstable and hard to ride.”

The Sada is relatively easy to fold up--a simple push on the seat collapses the frame and releases the wheels, its creator says.

Once it’s packed inside the backpack, it’s easy to carry around or push like a rolling suitcase. But is it actually easy to ride?

Sada says it’s not much different than riding a standard bike, but other designers say that isn't possible.

“This isn’t innovation--it's a hoax,” says Colin Owen, founder of urban cycling brand Sparse, who also teaches bike-frame design at California College of the Arts. “It's a render that is being pushed out to a population that can't discern a computer-generated image from a production model.”

Without spokes, the wheel can't be as strong. If it had the same amount of material as a typical wheel, it would “bend like a taco shell in a turn--a fine way of relieving the rider of his or her front teeth,” Owen says.

Can This Umbrella-Sized Folding Bike Actually Work?

Probably not, but it's at least an interesting experiment in bike physics.

How small can a folding bike become without sacrificing the ability to actually ride comfortably? The Sada Bike is one experiment: The full-sized frame folds down to the size of an umbrella, and full-sized wheels pop off so everything can fit into a backpack.

"It started as a joke," says Gianluca Sada, who created the bike as a design student. "But then I decided to devote my engineering study to developing it. Folding bikes are usually too small, with a frame and wheels that are portable but unstable and hard to ride."

The Sada is relatively easy to fold up—a simple push on the seat collapses the frame and releases the wheels, its creator says. Once it’s packed inside the backpack, it’s easy to carry around or push like a rolling suitcase. But is it actually easy to ride?

Sada says it’s not much different than riding a standard bike, but other designers say that isn't possible.

"This isn’t innovation—it's a hoax," says Colin Owen, founder of urban cycling brand Sparse, who also teaches bike-frame design at California College of the Arts. "It's a render that is being pushed out to a population that can't discern a computer-generated image from a production model."

Without spokes, the wheel can't be as strong. If it had the same amount of material as a typical wheel, it would "bend like a taco shell in a turn—a fine way of relieving the rider of his or her front teeth," Owen says. To help solve that problem, the design has extra material in the rims—but that means the wheels are about three times heavier than usual, making for slow starts and stops.

"There is room in bicycles, and even bicycle wheels for innovation," says Owen. "This particular design is either a naive design that remains willfully ignorant of physics, or it’s a cynical marketing push aimed at an unwitting population."

"This bike would fail in all performance metrics versus any low-end city bike minus the folding," he adds. "It would also perform less well than any number of folding bikes—Dahon, Tern, BikeFriday, and Brompton all make quality product that rides well and folds small."

Adele Peters is a staff writer at Co.Exist who focuses on sustainable design. Previously, she worked with GOOD, BioLite, and the Sustainable Products and Solutions program at UC Berkeley. You can reach her at apeters at fastcompany dot com. Continued